Normal Values of Second Trimester Maternal Serum Alpha Fetoprotein in Thai Pregnant Women

Abstract

Objective To establish the normal values of second trimester maternal serum alpha fetoprotein in Thai pregnant women.

Setting Department of Obstetrics and Gynaecology, Siriraj Hospital. Subjects During October 1992 and September 1993, pregnant women regardless of age and in their second trimester were recruited to the Siriraj Maternal Serum Alpha-Fetoprotein (MSAFP) Screening to detect Down syndrome and Neural Tube Defect.

Results From 2,485 women counseled, 770 were screened for serum alpha-fetoprotein. Amniocentesis was performed in 75 women age over 35 years. There were 1 neural tube defect, 3 stillbirths and 4 sets of twins in women with high MSAFP. One case of Down syndrome was found in a mother who was counseled but decided not to join the programme.

Conclusion The result of this study has firmly established the normal values of MSAFP in Thai pregnant women, from 15-21 weeks' gestation to detect common birth defects (DS and NTD) and women at increased risk of obstetric complications. Physician should be aware of the benefits of both high and low MSAFP screening not only for the prenatal detection of birth defects, but also for early identification of women at an increased risk of obstetric complications.